The 1997-2002 Ford Expedition 4WD is built with the following suspension components:
1997-2002 Ford Expedition 4WD Air Springs (x2)- commonly referred to as air bags, a plastic and rubber bag that uses pressurized air as a cushion (instead of a metal coil spring) to support the weight of the rear of the vehicle. These rubber air springs are the number one cause of all air suspension leaks. Since all air springs all go bad at about the same rate, if one is leaking, the others will not be far behind. For a proper repair, all of them need to be replaced at the same time.
1997-2002 Ford Expedition 4WD Front Air Shocks (x2)- Air shocks dampen vibration and reduce bounciness in the front of the vehicle. The contain a rubber bladder that fills with air sent by the compressor.
1997-2002 Ford Expedition 4WD Rear Gas Shocks (x2)- a type of shock absorber; has metal tubing filled with gas-charged hydraulic fluid that works independently of the air springs to dampen vibration and bounciness.
1997-2002 Ford Expedition 4WD Air Lines- tubes that carry pressurized air from the vehicle's onboard compressor to the air shocks and air springs in order to adjust the height of the vehicle.
1997-2002 Ford Expedition 4WD Solenoids (x4)- This vehicle is equipped with 4 solenoids. These plastic components work along with the suspension control module. The solenoids are responsible for regulating the air pressure in each air spring or air shock. Solenoids are a small piece of the suspension system but they play a big role in how well it functions. If a solenoid is not working properly, it will cause the vehicle's ride height to be unlevel.
1997-2002 Ford Expedition 4WD Compressor- This vehicle is equipped an onboard air suspension compressor, responsible for pumping up the air springs and shocks. When the air suspension starts leaking, the compressor is forced to run continuously to try and keep the air springs inflated. After a couple of days of running non-stop, the compressor will burn itself out. Replacing the compressor is a timely and expensive project to undertake.
1997-2002 Ford Expedition 4WD Dryer Assembly- This vehicle is equipped with a dryer assembly. The dryer assembly is responsible for getting moisture out of the air lines. Once the air suspension parts start to leak, moisture will build up throughout the air system. Moisture damages the air suspension components from the inside out. The dryer must be replaced whenever the compressor is replaced to prevent further damage.
1997-2002 Ford Expedition 4WD Suspension Control Module- This vehicle is equipped with a suspension control module. This module is the brain of the suspension system and it reads all of the signals that are being sent by the height sensors and determines if the vehicle needs to be raised or lowered.
1997-2002 Ford Expedition 4WD O-rings- Although they are the least expensive parts of the air suspension, they are responsible for maintaining the seal where all of the air lines connect. Be sure to replace the O-rings when repairing any air suspension system.